First, if you don't have it, grab the 1.94 beta. Then you should use mod folders. If you don't know how to make them, here's how:
1. Make a folder in your OperationFlashpoint directory, and name it, as an example, bas_isle. Then in this folder, put a folder named addons and put your Tonal files in this.
2. To run this, make a shortcut to the OFP program that you run and in the in "Target" field add stuff so it looks like this:
"C:\Program Files\Codemasters\OperationFlashpoint\FLASHPOINTBETA.EXE" -nosplash -mod=bas_isle
You can do this multiple mod folders by having something like this:
-mod=bas_isle;bas_units;hisky